聚合物凝胶溶液在岩心内动态运移及成胶形态的实验研究

Visualization of gel migration and gel formation in core

为探索更多聚合物凝胶在岩心中运移和封堵的信息,设计不同工艺参数的物模实验,并采用核磁成像技术对实验过程进行扫描跟踪,获得了凝胶溶液进入岩心、在岩心中运移、成胶后注水等阶段模拟图像。结果表明:聚合物凝胶溶液进入高低渗岩心时不存在明显的先后顺序,其选择性主要表现为高低渗岩心进入剂量的差别;在岩心中运移推进时,凝胶溶液前端会出现一定程度的“指进现象”,指进发生位置受岩心非均质性和重力双重影响,合理的注入速度和凝胶溶液黏度可以有效减轻指进程度;凝胶溶液注入剂量越大,聚集性越好,抗稀释能力越强;凝胶在高渗部位成胶促使注入水转向低渗,其放置的深度和成胶后的强度决定了低渗岩心启动的程度。

In order to obtain the information of gel migration and plugging in the core,it was designed the physical model experiments with different injected parameters,and the nuclear magnetic resonance(NMR)imaging technology was used to scan and track experimental processes.And then it was obtained visualization images for gel entering core,migration in core,and water injection after gelling.Experimental results show that there is no obvious sequence in the gel entering core,of which the selectivity is mainly shown by the difference between the doses into high and low permeability layers.When the gel is transported in the core pores,a certain degree of“fingering phenomenon”can occur at the front end of the gel,and the occurrence position of fingering is dually affected by the heterogeneity of core and the gravity.Reasonable injection rate and gel viscosity can effectively reduce the fingering degree.The higher the dose of gel implantation is,the better the aggregation is,and the stronger the anti-dilution ability is.The plugging of the hypertonic part causes the injected water to turn to low permeability.The depth and intensity of the gel placement determine the degree of low permeability starting.